(1) Field of the Invention
The present invention relates a technique for applying and holding a semiconductor wafer onto a ring frame via a adhesive tape, as a preceding process of a dicing treatment of the semiconductor wafer.
(2) Description of the Related Art
Following processes are performed in steps for cutting semiconductor chips out from semiconductor wafers:    formation of a mount frame by application and holding of a semiconductor wafer to a pressure sensitive adhesive tape (dicing tape) that has been applied on a ring frame;    transportation of the mount frame into a dicing process;    dicing treatment to the semiconductor wafer that has been applied and supported; and    dividing the chip.
The back side of the semiconductor wafer to be held on the ring frame is ground to be thinner, before the holding. An annular projected part is formed excluding the periphery part of the semiconductor wafer in order to avoid generation of warpage caused by accumulation of a working stress in the semiconductor wafer upon grinding, and to avoid breakage of the semiconductor wafer during handling accompanied by this thickness reduction process. This annular projected part keeps rigidity of the semiconductor wafer (refer to Japanese Unexamined Patent Publication No. 2007-103582 official report).
In recent years, thickness reduction of wafers are promoted from necessity of miniaturization of electronic equipments, and high density mounting etc. And therefore, semiconductor wafers having a smaller thickness of the order of approximately 10 micrometers tend to give cracking and chipping by warpage thereof. Furthermore, the semiconductor wafers have a higher risk of breakage in various kinds of process steps and handling. Therefore, the steps of application and holding of such a semiconductor wafers having a smaller thickness to the ring frame through a pressure sensitive adhesive tape for support may have problems of much higher risk of breakage.
Especially, the annular projected part left at the time of grinding of the semiconductor wafer must be removed before the dicing treatment. Accordingly, there may arise a possible problem of damaging of the semiconductor wafer caused by action, to the semiconductor wafers having a smaller thickness, of a working stress in removal of the annular projected part or by a stress accumulated in the wafer in back grinding processing immediately after removal of the annular projected part.